Reception apparatus and reception method

ABSTRACT

Method of scrambling signals, transmission point device, and user equipment using the method are provided. The method includes: sending an ID table to a user equipment through higher layer signaling, the ID table being a subset of the whole ID space and containing available IDs for the user equipment; notifying the user equipment an ID in the ID table to be used through physical layer signaling or UE specific higher layer signaling; generating a random seed based on the notified ID; initializing a scrambling sequence by the random seed; and scrambling the signals with the initialized scrambling sequence. The method of the disclosure, by combining physical layer signaling and higher layer signaling, may notify the used group ID and the blind detection space to a UE, wherein the blind detection for the UE is enabled and the signaling overhead is reduced.

BACKGROUND Technical Field

The present disclosure relates to the field of signals multiplexingmethod and reference signal design in communication system.

Description of the Related Art

DMRS (Demodulation Reference Signal) or UE (User Equipment) specificreference signal is one of RS (Reference Signals) used in LTE-A(Long-Term Evolution-Advanced) (release-10, release-11, etc.). DMRS isthe same precoded as the data part in a LTE-A system, so it can providethe channel estimation for demodulation.

FIG. 1 is a schematic diagram showing an example of DMRS multiplexed.FIG. 1 shows a structure of RB (resource block) and DMRS. In FIG. 1,there is shown one RB. The abscissa axis (T) of the RB represents time(OFDM symbols), and its vertical axis (F) represents width of frequencyband (sub-carriers). For the RB, the abscissa axis is divided into 14sections, each of which forms an OFDM symbol in the vertical axisdirection. The vertical axis is divided into 12 sections, each of whichforms a sub-carrier in the abscissa axis direction. Each small blockwithin the RB represents a RE (resource element), and all 12×14 REs ofthe RB form a sub-frame, which includes slot 1 and slot 2 along theabscissa axis direction. It is shown in FIG. 1 that the first threesymbols from the left side of the RB are used as a control region. Theremaining part of the RB is used to transmit data part, wherein thepredetermined number of DMRSs are included in the RB, and allocated indifferent predetermined locations of the RB.

It is shown in FIG. 1 that DMRSs are multiplied with OCC (orthogonalcover code) and scrambling sequence, respectively. FIG. 1 gives DMRSexamples of both rank 1 and rank 2 cases. For the rank 1 case, DMRS canuse OCC [1,1] or OCC [1,−1] for its only one layer; for the rank 2 case,DMRS uses both OCC [1,1] and OCC [1,−1] which are used for one of layersof DMRS respectively. Because two OCCs are orthogonal to each other, forthe rank 2 case, although two layers of DMRS occupy the samefrequency/time REs, the orthogonality between the two OCCs stillguarantees that two layers of DMRS are orthogonal to each other. It isnoted that different layers of DMRS can be called different DMRS ports.For example, in FIG. 1, DMRS using OCC [1,1] can be called port 7 andDMRS using OCC [1,−1] can be called port 8. When only port 7 or port 8is used, it is the rank 1 case; when both port 7 and port 8 are used, itis the rank 2 case.

On top of the OCC, there is a scrambling sequence [a1, a2, a3 . . . ,b1, b2, b3 . . . ] initialized by a random seed. In FIG. 1, in one RE,port 7 and 8 use the same scrambling sequence. The term “same scramblingsequence” here means that the scrambling sequence is initialized by thesame random seed. It is well known that a random seed in release-10 iscalculated by the following equation (1),

random seed=└n _(s)/2┘+1)·(2cell_id+1)·2 ¹⁶+SCID   (1)

wherein, n_(s) represents the slot number (2 slots in FIG. 1 constituteone subframe), cell_id represents a transmission point ID (cell ID), andSCID is a binary value. As shown from the equation (1), in release-10,the DMRS random seed is decided by the slot number, transmission pointID and a binary value SCID. It is possible that in one transmissionpoint, ports 7 and 8 can be configured with different values of SCID. Insuch case, port 7 and port 8 will use different scrambling sequences[a1, a2, a3 . . . ] and [b1, b2, b3 . . . ], for example. This mainlyintends for MU (multi-user) operation and it will be discussed later.

Because DMRS is the base of demodulation at the receiver side, how toset the DMRS random seed is very important for different scenarios,which will be elaborated on the following.

CoMP Scenario

JT (Joint Transmission) is one technique of CoMP (Coordinate MultiplePoints). FIG. 2 is a schematic diagram showing an exemplary JT scenario.It is shown in FIG. 2 that there are two transmission points (or cells)1 and 2, both of which transmits to one UE (such as a mobile phone,etc.) beams consisting of multiple RBs like the RB shown in FIG. 1. Thetwo RBs in FIG. 2 are simplified representations of the RB in FIG. 1.

The principle of JT operation is illustrated in FIG. 2. In JT operation,different transmission points transmit identical data and DMRS to a UE,and the identical data and DMRS from different transmission pointscombine over the air. So the UE can enjoy the diversity gain frommultiple transmission points. Therefore, for the JT operation, in orderto correctly combine signals from the multiple transmission points,identical DMRS from the multiple transmission points are necessary;otherwise, DMRS from the multiple transmission points cannot correctlybe combined over the air. In this sense, the same random seed forinitializing the scrambling sequence is necessary for JT operation.

However, it is likely that adjacent transmission points (cells) willhave different transmission point IDs. For example, in release-10,adjacent transmission points (cells) may have different transmissionpoint (cell) IDs. Because the parameter “cell_id” is involved in therandom seed calculation as shown in the above equation (1), iftransmission point IDs of different transmission points are different,their DMRS or DMRS scrambling sequences will also be different.Therefore, for JT operation, the key point is how to guarantee the sameDMRS random seed for different transmission points having differenttransmission point IDs.

Non-CoMP Scenario

FIG. 3 is a schematic diagram showing an exemplary non-CoMP scenario.Unlike the case of FIG. 2, in FIG. 3, signals transmitted from twoadjacent transmission points 1 and 2 are for different UEs, that is, UE1 and UE2, respectively, i.e., UE1 receives the signals from thetransmission point 1, and UE2 receives the signals from the transmissionpoint 2. In non-CoMP operation, since the position of DMRS in a RB isfixed, DMRSs from adjacent transmission points may interfere with eachother due to their overlapping in frequency and time resources. Forexample, as shown in FIG. 3, the signals transmitted from thetransmission point 1 to UE 1 and the signals transmitted from thetransmission point 2 to UE 2 overlap each other in frequency and timeresources, thus their DMRSs interfere with each other (as indicated bydashed arrows in FIG. 3). Therefore, in this case, different DMRSscrambling sequences for adjacent transmission points are necessary torandomize such ICI (inter-cell interference).

However, it is likely that adjacent transmission points (cells) willhave the same transmission point ID. For example, in release-11,adjacent transmission points may have the same transmission point ID.Because the parameter “cell_id” is involved in the DMRS random seedcalculation as shown in the above equation (1), if adjacent transmissionpoints have the same cell_id, DMRS scrambling sequences will beinitialized by the same random seed, and ICI is generated to the DMRS ofthe adjacent transmission points. Therefore, for non-CoMP operation, thekey point is how to guarantee different DMRS random seeds for adjacenttransmission points having the same transmission point ID.

FIG. 4 is a schematic diagram showing a comparison between JT scenarioand non-CoMP scenario. On the left side of FIG. 4, there is shown a JTscenario where adjacent transmission points have different transmissionpoint IDs. In this case, DMRS random seeds for initializing DMRSs oftransmission points 1 and 2 are respectively(└n_(s)/2┘+1)·(2cell_id1+1)·2¹⁶ and (└n_(s)/2┘+1)·(2cell_id2+1)·2¹⁶,both of which are obtained from the above equation (1) with a defaultSCID=0. Here, the parameter cell_id1 represents the transmission pointID of the transmission point 1 while the parameter cell_id2 representsthe transmission point ID of the transmission point 2, and cell_id1 isunequal to cell_id2. In order to correctly combine DMRSs from the twotransmission points 1 and 2 over the air, their DMRS random seeds arerequired to be identical especially in the case that their transmissionpoint IDs are not the same. In conclusion, for the JT scenario, the sameDMRS seed is necessary because DMRS combining over the air requiresidentical DMRS of JT transmission points.

On the right side of FIG. 4, there is shown a non-CoMP scenario whereadjacent transmission points have the same transmission point ID, i.e.cell_id1. In this case, DMRS random seeds for initializing DMRSs oftransmission points 1 and 2 respectively intended for UE1 and UE2 areboth (└n_(s)/2┘+1)·(2cell_id1+1)·2¹⁶, which is obtained from the aboveequation (1) with a default SCID=0. In order to randomize ICI (asindicated by dashed arrows in FIG. 4) between DMRS from the twotransmission points 1 and 2, their DMRS scrambling sequences arerequired to be different especially in the case that their transmissionpoint IDs are the same. In conclusion, for the non-CoMP, different DMRSseeds are necessary to randomize the ICI from overlapped DMRSs.

For the JT and non-CoMP scenarios as described above, it is concludedthat these two scenarios have conflict requirements on DMRS random seed:the JT operation requires the same DMRS random seed while the non-CoMPoperation requires different DMRS random seeds.

MU-MIMO Scenario

In addition to the above two scenarios, MU-MIMO (Multi-user MultipleInput-Multiple Output) scenario needs to be considered. FIG. 5 is aschematic diagram showing an exemplary MU-MIMO scenario. The principleof MU-MIMO operation is illustrated in FIG. 5. For MU-MIMO operation,two or more UEs are assigned to the shared frequency/time radioresource. It is shown in FIG. 5 that there are one transmission pointand two UEs, that is, UE1 and UE2, both of which share the samefrequency/time resource. Because the positions of DMRSs overlap, if oneUE such as UE1 can estimate the channel of interfering UE such as UE2from DMRS, then this UE such as UE1 can cancel the MU interference (asindicated by dashed arrows in FIG. 5) on its side.

Such UE side interference cancellation depends on whether or not a UEcan blindly detect the DMRS of interfering UE. FIG. 6 is a schematicdiagram showing an exemplary blind detection. The principle of the blinddetection is shown in FIG. 6. The freedom of DMRS inside onetransmission point (cell) is from 2 aspects: one is from DMRS randomseed by setting SCID=0 or 1; the other is from OCC by setting OCC as[1,1] or [1,−1] (or equivalently choosing DMRS port 7 or 8).Specifically, as shown in FIG.

6, assuming that the transmission point ID of the transmission point iscell_id1, it can be obtained that Seed0=(└n_(s)/2┘+1)·(2cell_id1+1)·2 ¹⁶and Seed1=(└n_(s)/2┘+1)·(2cell_id1+1)·2¹⁶+1 from the above equation (1)with SCID being 0 or 1. Combination of two different DMRS random seedsand two OCCs results in four different DMRSs: Seed0, OCC [1, 1]; Seed0,OCC [1, −1]; Seed1, OCC [1, 1]; Seed1, OCC [1, −1]. Each of the fourdifferent DMRSs is used for one UE. For example, as shown in FIG. 6, theDMRS with Seed0 and OCC [1, 1] is used for UEO; the DMRS with Seed0 andOCC [1, −1] is used for UE1; the DMRS with Seed1 and OCC [1, 1] is usedfor UE2; and the DMRS with Seed1 and OCC [1, −1] is used for UE3.Because there are totally 4 dimensions of DMRS, one UE can blindlydetect whether or not there are one or more of other three UEs' DMRSs onthe shared resource. This blind detection is feasible since thedetection space is limited within 4 dimensions of DMRS. It is notdifficult to find that DMRS random seed design largely affects suchblind detection. The release-10 DMRS random seed design enables suchblind detection, which should be considered as one design aspect forfurther improvement on DMRS random seed.

BRIEF SUMMARY

In one aspect of the present disclosure, there is provided a method ofscrambling signals assigned on predetermined radio resources of at leastone layer of resource blocks with the same time and frequency resources,comprising the steps of: generating a random seed based on the equationc_(init)=(└n_(s)/2┘+1)·(2*Max+1)·2¹⁶+(n_RNTI+2); initializing ascrambling sequence by the random seed; and scrambling the signals withthe initialized scrambling sequence, where Max=Maxim_value (cell_id),which represents the maximum value of transmission point IDs, c_(init)represents the random seed, n_(s) represents the slot number, and n_RNTIrepresents a user equipment specific ID.

In another aspect of the present disclosure, there is provided atransmission point device for transmitting to a user equipment signalsassigned on predetermined radio resources of at least one layer ofresource blocks with the same time and frequency resources, comprising:a random seed generation unit which generates a random seed based on theequation c_(init)=(└n_(s)/2┘+1)·(2*Max+1)·2¹⁶+(n_RNTI+2); aninitialization unit which initializes a scrambling sequence by therandom seed; a scrambling unit which scrambles the signals with theinitialized scrambling sequence; and a transceiver unit which transmitsthe resource blocks with the scrambled signals to the user equipment,where Max=Maxim_value(cell_id), which represents the maximum value oftransmission point IDs, c_(init) represents the random seed, n_(s)represents the slot number, and n_RNTI represents a user equipmentspecific ID.

In a further aspect of the present disclosure, there is provided a userequipment for receiving from a transmission point signals assigned onpredetermined radio resources of at least one layer of resource blockswith the same time and frequency resources, comprising: a transceiverunit which receives the resource blocks from the transmission point; anda demodulation unit which detects the resource blocks in time domainand/or frequency domain to obtain the signals, wherein, the signals arescrambled by a scrambling sequence initialized by a random seedgenerated based on the equationc_(init)=(└n_(s)/2┘+1)·(2*Max+1)·2¹⁶+(n_RNTI+2), whereMax=Maxim_value(cell_id), which represents the maximum value oftransmission point IDs, c_(init) represents the random seed, n_(s)represents the slot number, and n_RNTI represents a user equipmentspecific ID.

In a further aspect of the present disclosure, there is provided amethod of scrambling signals assigned on predetermined radio resourcesof at least one layer of resource blocks with the same time andfrequency resources, comprising the steps of: selecting a random seedfrom a first random seed generated based on a transmission point ID anda second random seed; initializing a scrambling sequence by the selectedrandom seed; and scrambling the signals with the initialized scramblingsequence.

In a further aspect of the present disclosure, there is provided atransmission point device for transmitting to a user equipment signalsassigned on predetermined radio resources of at least one layer ofresource blocks with the same time and frequency resources, comprising:a selection unit which selects a random seed from a first random seedgenerated based on a transmission point ID and a second random seed; aninitialization unit which initializes a scrambling sequence by theselected random seed; a scrambling unit for scrambling the signals withthe initialized scrambling sequence; and a transceiver unit whichtransmits the resource blocks with the scrambled signals to the userequipment.

In a further aspect of the present disclosure, there is provided a userequipment for receiving from a transmission point signals assigned onpredetermined radio resources of at least one layer of resource blockswith the same time and frequency resources, comprising: a transceiverunit which receives the at least one layer of resource blocks from thetransmission point; and a demodulation unit which detects the resourceblocks in time domain and/or frequency domain to obtain the signals,wherein, the signals are scrambled by a scrambling sequence initializedby a random seed selected from a first random seed generated based on atransmission point ID and a second random seed.

In a further aspect of the present disclosure, there is provided amethod of scrambling signals assigned on predetermined radio resourcesof at least one layer of resource blocks with the same time andfrequency resources, comprising the steps of: sending an ID table to auser equipment through higher layer signaling, the ID table being asubset of a whole ID space and containing available IDs for the userequipment; notifying the user equipment of a ID in the ID table to beused through physical layer signaling or UE specific higher layersignaling; generating a random seed based on the notified ID;initializing a scrambling sequence by the random seed; and scramblingthe signals with the initialized scrambling sequence.

In a further aspect of the present disclosure, there is provided atransmission point device for transmitting to a user equipment signalsassigned on predetermined radio resources of at least one layer ofresource blocks with the same time and frequency resources, comprising:a notification unit which notifies the user equipment of an ID in an IDtable to be used through physical layer signaling or UE specific higherlayer signaling, wherein the ID table is sent to the user equipmentthrough higher layer signaling, the ID table being a subset of a wholeID space and containing available IDs for the user equipment; a randomseed generation unit which generates a random seed based on the notifiedID; an initialization unit which initializes a scrambling sequence bythe random seed; a scrambling unit which scrambles the signals with theinitialized scrambling sequence; and a transceiver unit which transmitsthe resource blocks with the scrambled signals to the user equipment.

In a further aspect of the present disclosure, there is provided a userequipment for receiving from a transmission point device signalsassigned on predetermined radio resources of at least one layer ofresource blocks with the same time and frequency resources, comprising:a transceiver unit which receives the resource blocks and physical layersignaling or UE specific higher layer signaling from the transmissionpoint device, wherein the physical layer signaling or the UE specifichigher layer signaling notifies the user equipment of a ID in an IDtable to be used, wherein the ID table is sent to the user equipmentthrough higher layer signaling, the ID table being a subset of a wholeID space and containing available IDs for the user equipment; ademodulation unit which detects the resource blocks in time domainand/or frequency domain to obtain the signals, wherein, the signalsbeing scrambled by a scrambling sequence initialized by a random seedgenerated based on the notified ID.

In the present disclosure, by generating random seeds for initializingscrambling sequences for DMRSs based on UE specific IDs or group IDs,identical DMRS from multiple transmission points are guaranteed for theJT scenarios while different DMRSs from adjacent transmission points areguaranteed for the non-CoMP scenarios. Further, by switching betweenrelease-10 DMRS random seeds and UE specific DMRS random seeds, theblind detection can be enabled and the orthogonality between UEs can bekept in MU operation, while the conflict requirements for JT andnon-CoMP operation can be solved in non-MU operation. Moreover, bycombining physical layer signaling and higher layer signaling to notifythe used group ID and the blind detection space to a UE, the blinddetection for the UE is enabled and the signaling overhead is reduced.

The foregoing is a summary and thus contains, by necessity,simplifications, generalization, and omissions of details; consequently,those skilled in the art will appreciate that the summary isillustrative only and is not intended to be in any way limiting. Otheraspects, features, and advantages of the devices and/or processes and/orother subject matters described herein will become apparent in theteachings set forth herein. The summary is provided to introduce aselection of concepts in a simplified form that are further describedbelow in the Detailed Description. This summary is not intended toidentify key features or essential features of the claimed subjectmatter, nor is it intended to be used as an aid in determining the scopeof the claimed subject matter.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

The foregoing and other features of the present disclosure will becomemore fully apparent from the following description and appended claims,taken in conjunction with the accompanying drawings. Understanding thatthese drawings depict only several embodiments in accordance with thedisclosure and are, therefore, not to be considered limiting of itsscope, the disclosure will be described with additional specificity anddetail through use of the accompanying drawings, in which:

FIG. 1 is a schematic diagram showing an example of DMRS multiplexed;

FIG. 2 is a schematic diagram showing an exemplary JT scenario;

FIG. 3 is a schematic diagram showing an exemplary non-CoMP scenario;

FIG. 4 is a schematic diagram showing a comparison between JT scenarioand non-CoMP scenario;

FIG. 5 is a schematic diagram showing an exemplary MU-MIMO scenario;

FIG. 6 is a schematic diagram showing an exemplary blind detection;

FIG. 7 is a block diagram showing a transmission point device accordingto the first embodiment of the present disclosure;

FIG. 8 is a block diagram showing a UE according to the first embodimentof the present disclosure;

FIG. 9 is a schematic diagram showing an example of MU-MIMO DMRSsmultiplexed;

FIG. 10 is a block diagram showing a transmission point device accordingto the third embodiment of the present disclosure;

FIG. 11 shows a table for notifying UEs of DMRS ports and DMRS randomseeds in release-10 as defined in TS 36.212;

FIG. 12 shows a table for notifying UEs of the selection betweenrelease-10 random seeds and UE specific random seeds according to thethird embodiment of the present disclosure;

FIG. 13 shows another table for notifying UEs of the selection betweenrelease-10 random seeds and UE specific random seeds according to thethird embodiment of the present disclosure;

FIG. 14 is a diagram showing a flow chart of a method of scramblingsignals according to the fifth embodiment of the present disclosure;

FIG. 15 is a diagram showing a flow chart of a method of scramblingsignals according to the sixth embodiment of the present disclosure;

FIG. 16 is a schematic diagram showing the configuration of group IDsaccording to the seventh embodiment of the present disclosure;

FIG. 17 shows an example of a structured group ID table configured to aUE through higher layer signaling according to the ninth embodiment ofthe present disclosure;

FIG. 18 shows a table used for Part I of physical layer signalingaccording to the tenth embodiment of the present disclosure;

FIG. 19 shows a table used for Part III of physical layer signalingaccording to the tenth embodiment of the present disclosure;

FIGS. 20A and 20B are schematic diagrams showing a complete examplewhere a transmission point use the higher layer signaling and physicallayer signaling as defined in the ninth and the tenth embodiments toconfigure a UE when the UE moves from the center to the edge of thetransmission point;

FIG. 21 is a schematic diagram showing a case that physical layersignaling is lost due to PDCCH failure according to the eleventhembodiment of the present disclosure;

FIG. 22 is a schematic diagram showing a case that the asynchronizationbetween eNB and UE is avoided by combining with an Ack/Nck mechanismaccording to the eleventh embodiment of the present disclosure;

FIG. 23 shows an example of a structured “x” ID table configured to a UEthrough higher layer signaling according to the twelfth embodiment ofthe present disclosure; and

FIG. 24 is a diagram showing a flow chart of a method of scramblingsignals according to the thirteenth embodiment of the presentdisclosure.

DETAILED DESCRIPTION

In the following detailed description, reference is made to theaccompanying drawings, which form a part hereof. In the drawings,similar symbols typically identify similar components, unless contextdictates otherwise. It will be readily understood that the aspects ofthe present disclosure can be arranged, substituted, combined, anddesigned in a wide variety of different configurations, all of which areexplicitly contemplated and make part of this disclosure.

First Embodiment

FIG. 7 is a block diagram showing a transmission point device accordingto the first embodiment of the present disclosure.

The transmission point device 700 according to the first embodiment ofthe present disclosure is used for communicating with a UE in acommunication system. The transmission point device 700 transmits, tothe UE, RS signals which are assigned on predetermined locations (radioresource, which means the time and/or frequency resource such assub-carrier, sub-frame, etc.) of at least one layer of resource blockswith the same time and frequency resources. As shown in FIG. 7, thetransmission point device 700 may include a random seed generation unit701, an initialization unit 702, a scrambling unit 703, and atransceiver unit 704. The random seed generation unit 701 generates arandom seed based on a UE specific ID. The initialization unit 702initializes a scrambling sequence by the random seed generated in therandom seed generation unit 701. The scrambling unit 703 scrambles thesignals with the scrambling sequence initialized in the initializationunit 702. The transceiver unit 704 transmits the resource blocks withthe signals scrambled in the scrambling unit 703 to the UE. It should benoted that RS signals here can be any kinds of RS signals such as DMRSand the like. For sake of simplicity, the following description willfocus on the DMRS as an example.

The transmission point device 700 according to the present disclosuremay further include a CPU (Central Processing Unit) 710 for executingrelated programs to process various data and control operations ofrespective units in the transmission point device 700, a ROM (Read OnlyMemory) 713 for storing various programs required for performing variousprocess and control by the CPU 710, a RAM (Random Access Memory) 715 forstoring intermediate data temporarily produced in the procedure ofprocess and control by the CPU 710, and/or a I/O (Input/Output) unit 717for inputting for outputting various programs, data and so on. The aboverandom seed generation unit 701, initialization unit 702, scramblingunit 703, transceiver unit 704, CPU 710, ROM 713, RAM 715 and/or I/Ounit 717 etc. may be interconnected via data and/or command bus 720 andtransfer signals between one another.

Respective units as described above do not limit the scope of thepresent disclosure. According to one embodiment of the disclosure, thefunction of any of the above random seed generation unit 701,initialization unit 702, scrambling unit 703 and transceiver unit 704may also be implemented by functional software in combination with theabove CPU 710, ROM 713, RAM 715 and/or I/O unit 717 etc.

Since the operations of the initialization unit 702, the scrambling unit703 and the transceiver unit 704 in the transmission point device 700are well known to the skilled in the art, the detailed descriptionthereof is omitted here in order to avoid confusing inventive points ofthe present invention. The detailed description will be given to theoperation of the random seed generation unit 701 of the transmissionpoint device 700 below.

The above random seed generation unit 701 generates a random seed forinitializing a scrambling sequence for RS signals based on a UE specificID instead of using a transmission point ID as shown in the equation(1). Here, such a UE specific ID may be a global UE specificidentification number such as IMSI (International Mobile SubscriberIdentification Number). Alternatively, it may also be a UE specific IDassigned to the UE when the UE accesses to a LTE network, such as c-RNTI(Cell_Radio Network Temporary Identifier).

As an example, equation (2) is used for generating a random seed forinitializing a scrambling sequence for RS signals, such as DMRS, basedon c-RNTI as follows.

c _(init)=(└n _(s)/2┘+1)·(n_RNTI)·2¹⁶   (2)

Wherein, c_(init) represents the generated random seed, n_(s) representsthe slot number, and n_RNTI is a parameter defined in 3GPP TS 36.213,representing a UE specific ID. It is noted that the parameter “c-RNTI”is a subset of “n-RNTI”, which represents different RNTIs, and the“n-RNTI” is the “c-RNTI” in most cases. Thereby, the random seedgeneration unit 701 may generate the random seed from the equation (2).

Comparing the equation (2) in the present embodiment with the aboveequation (1) for generating DMRS random seed in release-10, it is foundthat the parameter cell_id in the equation (1) is no longer involved inthe equation (2). Thus, the conflict requirements on DMRS random seedfor the JT scenario and the non-CoMP scenario as shown in FIG. 4 aresolved by using the equation (2). Specifically, in the JT scenario,since adjacent transmission points (cells) all use UE specific IDs togenerate DMRS random seeds and accordingly the scrambling sequences,they have the same DMRS even in a case of having different transmissionpoint IDs. In the non-CoMP scenario, since different UEs have differentUE specific IDs which are used to generate DMRS random seeds andaccordingly the scrambling sequences, they have different DMRSs even ina case of having the same transmission point ID, so that overlappedDMRSs on adjacent transmission points will have different scramblingsequences to randomize the potential ICI.

FIG. 8 is a block diagram showing a UE according to the first embodimentof the present disclosure. The UE 800 according to the first embodimentof the present disclosure is used for communicating with a transmissionpoint device in a communication system. The UE 800 receives from thetransmission point device the RS signals which are assigned onpredetermined locations (radio resource, which means the time and/orfrequency resource such as sub-carrier, sub-frame, etc.) of at least onelayer of resource blocks with the same time and frequency resources. Asshown in FIG. 8, the UE 800 may include a transceiver unit 801 and ademodulation unit 802. The transceiver unit 801 receives the resourceblocks from the transmission point device. The demodulation unit 802detects the resource blocks in time domain and/or frequency domain toobtain the RS signals, wherein the signals are scrambled by a scramblingsequence initialized by a random seed generated based on a UE specificID.

As described previously with reference to the transmission point device700, a random seed for initializing a scrambling sequence for RS signalssuch as DMRS may be generated based on a UE specific ID, such as c-RNTIas shown in the equation (2). That is, according to the presentembodiment, the random seed may be generated from the equation (2). Itshould be noted that the equation (2) is only exemplary and the UEspecific ID is not limited to c-RNTI, instead, it may be IMSI or otherUE specific IDs which are not listed in the present disclosure.

The UE 800 according to the present disclosure may further include a CPU(Central Processing Unit) 810 for executing related programs to processvarious data and control operations of respective units in the UE 800, aROM (Read Only Memory) 813 for storing various programs required forperforming various process and control by the CPU 810, a RAM (RandomAccess Memory) 815 for storing intermediate data temporarily produced inthe procedure of process and control by the CPU 810, and/or a I/O unit817 for inputting or outputting various programs, data and so on. Theabove transceiver unit 801, demodulation unit 802, CPU 810, ROM 813, RAM815 and/or I/O unit 817 etc. may be interconnected via data and/orcommand bus 820 and transfer signals between one another.

Respective units as described above do not limit the scope of thepresent disclosure. According to one embodiment of the disclosure, thefunction of any of the above transceiver unit 801 and demodulation unit802 may also be implemented by functional software in combination withthe above CPU 810, ROM 813, RAM 815 and/or I/O unit 817 etc.

According to the present embodiment, by generating random seeds forinitializing scrambling sequences for the RS signals based on the UEspecific IDs, the conflict requirements on DMRS random seed for the JTscenario and the non-CoMP scenario as shown in FIG. 4 are solved, thatis, the identical DMRS from multiple transmission points are guaranteedfor the JT scenarios while different DMRSs from adjacent transmissionpoints are guaranteed for the non-CoMP scenarios.

Second Embodiment

Comparing the equation (2) brought forward in the first embodiment andthe equation (1) for DMRS random seed generation in release-10, it isfound that the random seeds generated from the equation (2) may collidewith the random seeds generated from the equation (1), because the rangeof the parameter n_RNTI in the equation (2) is 0˜2¹⁶−1. Considering acase where the random seeds generated from the equation (1) are assignedfor release-10 UEs while the random seeds generated from the equation(2) are assigned for release-11 UEs, Such collision may produce problemsif release-10 UEs with the random seeds generated from the equation (1)and release-11 UEs with the random seeds generated from the equation (2)coexist.

To resolve the above collision problem, equation (3) gives one exemplaryimprovement on the equation (2) in the first embodiment as follows

c _(init)=(└n _(s)/2┘+1)·(2*Max+1)·2¹⁶+(n_RNTI+2)   (3)

Where Max=Maxim_value (cell_id), representing the maximum value oftransmission point IDs, and parameters c_(init), n_(s) and n_RNTI arethe same as those in the equation (2).

Comparing the equation (3) with the equation (1), it is easy to findthat since the parameter Max in the equation (3) corresponds to themaximum value of cell_ids, Max≥cell_id and accordingly2*Max+1≥2cell_id+1, such that(└n_(s)/2┘+1)·(2*Max+1)·2¹⁶≥(└n_(s)/2┘+1·(2cell_id+1)·2¹⁶. Furthermore,the parameter SCID in the equation (1) is commonly set as 0 or 1, sothat SCID<2. Therefore,(└n_(s)/2┘+1)·(2*Max+1)·2¹⁶+2>(└n_(s)/2┘+1)·(2cell_id+1)·2¹⁶+SCID. Thus,it is out of question that the random seeds generated from the equation(3) are always larger than release-10 DMRS random seeds generated fromthe equation (1). Using the random seed generation equation (3), theabove random seed collision problem can be solved. Note that theequation (3) is only one exemplary improvement on the equation (2) andresolution of the above random seed collision problem is not limitedthereto. For example, the constant “2” in the equation (3) is a criticalvalue and can be replaced by an arbitrary number larger than 2. Thereby,according to the present embodiment, for a transmission point device(for example, 700) or a UE (for example, 800), the random seed may begenerated from the equation (3).

According to the present embodiment, by improving the UE specific randomseed generation equation (2) of the second embodiment, collision betweenthe UE specific random seeds and release-10 random seeds can be avoidedwhile the conflict requirements on DMRS random seeds for the JT scenarioand the non-CoMP scenario as shown in FIG. 4 is solved.

Third Embodiment

As described before, the blind detection of DMRS at a receiver side canhelp an UE to estimate the interference in MU-MIMO operation. However,if the equation (2) or (3) is used to generate DMRS random seeds, the UEmay not be able to perform the blind detection, because there are toomany possibilities for the UE specific random seeds or the blinddetection space is too large in this case. For example, since there are2¹⁶ possibilities for the value of n_RNTI in both the equation (2) andthe equation (3) as discussed above, there are 2 ¹⁶ possibilities forrandom seeds generated from the equation (2) or (3), which results inmuch more dimensions of DMRS than those of FIG. 6 using the release-10DMRS random seed generation equation (1). It is difficult to perform theblind detection of DMRS in a case of too many dimensions of DMRS.

Orthogonality between MU-MIMO DMRS ports is another concern for theequation (2) and the equation (3). As shown in FIG. 5, there are twoUEs, i.e. UE1 and UE2, in the MU-MIMO case. It is assumed that UE1 isassigned with DMRS port 7 (OCC [1,1]) and UE2 is assigned with DMRS port8 (OCC [1,−1]) and that UE1 and UE2 are both configured with UE specificrandom seeds generated from the equation (2) or (3). Therefore, it isfound that two different sequences are scrambled to the two orthogonalDMRS ports (the ports 7 and 8) respectively as illustrated in FIG. 9.FIG. 9 is a schematic diagram showing an example of MU-MIMO DMRSsmultiplexed. In FIG. 9, the port 7 corresponding to OCC [1, 1] isscrambled by the scrambling sequence [A1, B1 . . . ] while the port 8corresponding to OCC [1, −1] is scrambled by the scrambling sequence[C1, D1 . . . ]. The two scrambling sequences are initializedrespectively by two different random seeds generated from the aboveequation (2) or (3) based on their respective UE specific IDs. Here, if(A1*)C1+(B1*)D1=0 or [A1,B1]⊥[C1,D1], the orthogonality between the twoDMRS ports is destroyed. Therefore, in such a MU-MIMO case, to keep theDMRS orthogonality between MU UEs, it is necessary to use the samescrambling sequence for two MU UEs if they are assigned with orthogonalDMRS ports (for example, the port 7 and the port 8).

Considering that the release-10 DMRS random seed design enables blinddetection as discussed above with reference to FIG. 5 and FIG. 6, thebasic idea of the present embodiment is to switch between the release-10DMRS random seeds as generated from the equation (1) and the UE specificDMRS random seeds as generated from the equation (3) in order to resolvethe above two problems encountered in a case of generating DMRS randomseeds based on UE specific IDs. Specifically, when UEs are in MU-MIMOoperation, the system configures the UEs with the release-10 DMRS randomseeds as generated from the release-10 random seed generation equation(1); otherwise, the UEs are configured with the UE specific random seedsas generated from the equation (3).

The advantage of such a switch is that: when the UEs are in MUoperation, the release-10 random seeds can enable the blind detectionand keep the orthogonality between them; when the UEs are not in MUoperation, the UE specific random seeds can satisfy the conflictrequirements for both JT and non-CoMP operations.

FIG. 10 is a block diagram showing a transmission point device accordingto the third embodiment of the present disclosure. The transmissionpoint device 1000 according to the third embodiment of the presentdisclosure is used for communicating with a UE in a communicationsystem. Similarly to the transmission point device 700 of the firstembodiment, the transmission point device 1000 transmits, to a UE, RSsignals which are assigned on predetermined locations (radio resource,which means the time and/or frequency resource such as sub-carrier,sub-frame, etc.) of at least one layer of resource blocks with the sametime and frequency resources. As shown in FIG. 10, the transmissionpoint device 1000 may include a selection unit 1001, an initializationunit 1002, a scrambling unit 1003, and a transceiver unit 1004. Theselection unit 1001 selects a random seed from a first random seedgenerated based on a transmission point ID and a second random seedgenerated based on a UE specific ID. The initialization unit 1002initializes a scrambling sequence by the random seed selected in theselection unit 1001. The scrambling unit 1003 scrambles the signals withthe scrambling sequence initialized in the initialization unit 1002. Thetransceiver unit 1004 transmits the resource block with the signalsscrambled in the scrambling unit 1003 to the UE. It should be noted thatthe RS signals here can be any kinds of RS signals such as DMRS and thelike.

The transmission point device 1000 according to the present disclosuremay further include a CPU 1010, a ROM 1013, a RAM 1015 and/or I/O unit1017, all of which are the same as those in the transmission pointdevice 700 of the first embodiment. For the sake of simplicity, thedescription of their functions is omitted here. Also, the aboveselection unit 1001, initialization unit 1002, scrambling unit 1003,transceiver unit 1004, CPU 1010, ROM 1013, RAM 1015 and/or I/O unit 1017etc. may be interconnected via data and/or command bus 1020 and transfersignals between one another.

Respective units as described above do not limit the scope of thepresent disclosure. According to one embodiment of the disclosure, thefunction of any of the above selection unit 1001, initialization unit1002, scrambling unit 1003 and transceiver unit 1004 may also beimplemented by functional software in combination with the above CPU1010, ROM 1013, RAM 1015 and/or I/O unit 1017 etc.

According to the present embodiment, the UE shown in FIG. 8 may alsoreceive from the transmission point device 1000 the resource blocks, andobtain the signals which are scrambled by a scrambling sequenceinitialized by a random seed selected from a first random seed generatedbased on a transmission point ID and a second random seed generatedbased on a UE specific ID.

To implement the switch between the release-10 DMRS random seeds and theUE specific DMRS random seeds, there should be a signaling to notify theUEs about the switch. One simple way is to add one bit signaling flag incurrent PHY (physical) signaling for the switch. It should be noted thata way of notifying the UEs of the switch is not limited to the way asdescribed above.

According to the present embodiment, although not shown in FIG. 10, thetransmission point device 1000 may also include a notification unitwhich notifies the user equipment of the switch between (selection of)the first random seed and the second random seed by adding one bitsignaling as a switch flag. The first random seed may be generated fromthe equation (1). The second random seed is different from the firstrandom seed. The second random seed may be generated from the equation(3).

According to the present embodiment, although not shown in FIG. 8, thetransceiver unit 802 in the user equipment 800 may also receive amessage which indicates the selection of the first random seed and thesecond random seed with one bit signaling as a switch flag, in which thefirst random seed may be generated from the equation (1), the secondrandom seed is different from the first random seed, and the secondrandom seed may be generated from the equation (3).

According to the present embodiment, by switching between the release-10DMRS random seeds and the UE specific DMRS random seeds, the blinddetection can be enabled and the orthogonality between the UEs can bekept in MU operation, while the conflict requirements for both JT andnon-CoMP operations can be solved in non-MU operation.

The following description will focus on how to notify the UEs of theselection of the release-10 DMRS random seeds and the UE specific DMRSrandom seeds.

FIG. 11 shows a table for notifying the UEs of DMRS ports and DMRSrandom seeds in the release-10 as defined in TS 36.212. As shown in FIG.11, the table is divided into two parts, and the left part correspondsto one codeword case while the right part corresponds to a case of twocodewords. In the left part (the one codeword case), the left columngives eight values 0-7 in the one codeword and the right columnrepresents messages indicated by the values. Except that the value 7 isreserved, the other seven values 0-6 indicate different combinations ofDMRS ports and DMRS random seeds respectively. Specifically, the value 0indicates a case of one layer transmission with the port 7 and SCID=0;value 1 indicates a case of one layer transmission with the port 7 andSCID=1; the value 2 indicates a case of one layer transmission with theport 8 and SCID=0; value 3 indicates a case of one layer transmissionwith the port 8 and SCID=1; the value 4 indicates a case of two layertransmission with the ports 7-8 and SCID=0; the value 5 indicates a caseof three layer transmission with the ports 7-9 and SCID=0; and the value6 indicates a case of four layer transmission with the ports 7-10 andSCID=0.

The right part (the case of two codewords) of the table in FIG. 11 issimilar with the left part. That is, eight values 0-7 in the twocodeword indicate respectively eight different combinations of DMRSports and DMRS random seeds respectively. Specifically, the value 0indicates a case of two layer transmission with the ports 7-8 andSCID=0; value 1 indicates a case of two layer transmission with theports 7-8 and SCID=1; the value 2 indicates a case of three layertransmission with the ports 7-9 and SCID=0; value 3 indicates a case offour layer transmission with the ports 7-10 and SCID=0; the value 4indicates a case of five layer transmission with the ports 7-11 andSCID=0; the value 5 indicates a case of six layer transmission with theports 7-12 and SCID=0; the value 6 indicates a case of seven layertransmission with the ports 7-13 and SCID=0; and the value 7 indicates acase of eight layer transmission with the ports 7-14 and SCID=0.

On PHY signaling, different values are transmitted on the air interface.A UE receives different values and interprets the meanings of the valuesaccording to the table of FIG. 11.

From FIG. 11, it is found that SCID equals 0 in most of the cases, thatis, the cases of the values 0, 2 and 4-6 in the left part correspondingto the one codeword and the cases of the values 0 and 2-7 in the rightpart corresponding to the two codewords, which gives a hint that theSCID may be used as an implicit signaling to notify the UEs of therandom seed selection. FIG. 12 shows a table for notifying the UEs ofthe selection of the release-10 random seeds and the UE specific randomseeds according to the present embodiment. In FIG. 12, 8 values are usedto indicate release-11 messages in both cases of one codeword and twocodewords.

By comparing the table of FIG. 12 and the table of FIG. 11, it is foundthat “SCID=0 ” in FIG. 11 is replaced by “UE specific seed” (UE specificrandom seed) in release-11 message in FIG. 12, and “SCID=1 ” in FIG. 11is replaced by “rel-10 seed (SCID=0)” (release-10 random seed) in FIG.12. Here, “rel-10 seed (SCID=0)” represents the following equation (4)which is obtained from the equation (1) with SCID being set as 0.

c _(init)=(└n _(s)/2┘+1)·(2N _(ID) ^(cell)+1)·2¹⁶   (4)

Wherein, the parameter N_(ID) ^(cell) is equivalent to the parametercell_id in the equation (1), representing the value of a transmissionpoint ID. “UE specific seed” in FIG. 12 means random seeds generatedfrom the equation (3) based on the UE specific IDs. The table shown inFIG. 12 uses “SCID” in the table of FIG. 11 as an implicit signaling tonotify the UEs of the selection of the release-10 random seeds and theUE specific random seeds. That is, when SCID in FIG. 11 is 0, itindicates to the selection of the UE specific random seed; when SCID inFIG. 11 is 1, it indicates the selection of the release-10 random seedas generated from the equation (4).

Therefore, according to the present embodiment, by using SCID as aswitch flag, the UEs can be notified of the switch between (selectionof) the release-10 random seeds and the UE specific random seeds throughthe current PHY signaling without adding one bit signaling flag.

It should be noted that the table shown in FIG. 12 is only one example.It is easy to see that if the relationship between the “value” and the“message” in the table of FIG. 12 is re-ordered, it has the same effectsas before. But after re-ordering, the “SCID” cannot be interpreted as aswitch flag.

It should be noted that the release-10 DMRS random seed has twopossibilities, that is, SCID=0 (the equation (4)) and SCID=1. However,in the table in FIG. 12, when it is switched to the release-10 DMRSrandom seed (rel-10 seed), only the SCID=0 case is retained. It is foundwith reference to FIG. 6 that if the blind detection is enabled in thiscase, combinations of only SCID=0 case and two OCCs ([1, 1] and [1, −1])result in only two dimensions of the blind detection. However, therelease-10 supports four dimensions of the blind detection in fact.

In the present embodiment, in order to overcome the above constraint onthe dimensions of the blind detection in the table of FIG. 12, the tabledefined in TS 36.212 (the table of FIG. 11) may be modified instead ofintroducing a new bit of switch flag to notify the UE of the RS randomseed switching.

The present embodiment starts from analysis of the table in FIG. 12.First, it is found that the value 7 in one codeword case is a reservedvalue. Second, it is found that port 7 (OCC [1,1]) and port 8 (OCC[1,−1]) can both support the UE specific random seeds. Furthermore, fornon-MU operation (including JT operation and non-CoMP operation), theuse of UE specific random seeds is enough as described in the first andthe second embodiments; for MU operation, DMRS random seed is switchedto the release-10 random seed case. Therefore, it can be concluded thatone of ports 7 and 8 is configured with the UE specific random seed isenough.

Based on the above analysis, the basic idea of the present embodimentis: 1) DMRS random seeds for one layer transmission is the same as thosein the release-10 for the MU scenario; 2) the reserved value 7 in thetable for current signaling in FIG. 11 is utilized; 3) one of port 7 orport 8 (instead of both port 7 and port 8) is configured with the UEspecific random seed for the non-MU scenario. FIG. 13 shows anothertable for notifying the UEs of the switch between (selection of) therelease-10 random seeds and the UE specific random seeds according tothe present embodiment. The table shown in FIG. 13 is an improvement ofthe table shown in FIG. 12. Since only the left part (the one codewordcase) of the table in FIG. 12 is modified in the present embodimentwhile the right part (the case of two codewords) remains unchanged, forsake of clarity, only the modified left part is shown in FIG. 13.

In FIG. 13, for MU operation, the release-10 random seeds are normalrelease-10 random seeds as generated from the equation (1). That is, themessages corresponding to values 0-3 are the same as those in the tableof FIG. 11. Thereby, four dimensions of blind detection are assured. Themessages corresponding to values 4-6 in FIG. 13 are the same as those inthe table of FIG. 12, wherein the UE specific random seed is the randomseed generated from the equation (3). The value 7 which is reserved inFIG. 11 and FIG. 12 indicates the case of one layer transmission withport 7 and the UE specific seed in FIG. 12. It is seen that because ofusing the reserved value and configuring just one port (for example,port 7) with the UE specific random seed for rank 1 transmission, it ispossible to retain the normal release-10 random seeds in the table shownin FIG. 13. Here, it is noted that the value 7 may indicate the case ofone layer transmission with port 8 and the UE specific seed,alternatively.

According to the present embodiment, the MU blind detection space is thesame as that in release-10 while there is no need to introduce a newsignaling bit to notify the UEs of the DMRS random seed switch.

It is noted that the table of FIG. 13 is only one example, andre-ordering the relationship between the “value” and the “message” inthe table has the same effects as described above. Furthermore, it willbe appreciated by those skilled in the art that it is also possible toretain only one value of “0” or “2” in the table of FIG. 12 in the sensethat configuring one port (port 7 or 8) with the UE specific random seedfor rank 1 transmission of the MU scenario is sufficient. Specifically,if value 0 is retained, value 1-3 and 7 may be used to indicaterespectively four combinations of different ports and differentrelease-10 random seeds with respect to one layer transmission.Similarly, if value 2 is retained, value 0, 1, 3 and 7 may be used toindicate respectively four combinations of different ports and differentrelease-10 random seeds with respect to one layer transmission.

The aforesaid examples all focus on downlink DMRS cases. In fact,similar problem also occurs on uplink DMRS cases. For example, in UL(uplink) DMRS of PUSCH (Physical Uplink Shared Channel) case, thescrambling sequences are initialized by random seeds based ontransmission point IDs. If adjacent transmission points have the sametransmission point ID, DMRSs of PUSCH among adjacent transmission pointsmay interfere with each other. In that case, using UE specific randomseeds which are based on the UE specific IDs such as n_RNTI is betterthan using transmission point specific random seeds which are based onfor example transmission point IDs.

According to the present embodiment, uplink RS signals may be scrambledby a scrambling sequence initialized by a random seed generated based ona UE specific ID.

According to the present embodiment, uplink RS signals may also bescrambled by a scrambling sequence initialized by a random seed which isselected from a first random seed generated based on a transmissionpoint specific ID and a second random generated based on a UE specificID.

The above description all focus on the RS (for example, DMRS) design. Infact, scrambling is also applied to data channels, such as PDSCH(Physical Downlink Shared Channel) or PUSCH, and control channels, suchas PDCCH (Physical Downlink Control Channel) or PUCCH (Physical UplinkControl Channel). A scrambling sequence initialized by a random seed isscrambled to a data or control channel to randomize the potential ICIamong cells or transmission points. Transmission point IDs are alsoinvolved in the random seed generation. Therefore, if adjacent cells ortransmission points have different transmission point IDs, the JToperation will encounter problems as described before. In this case,using the UE specific random seeds which is based on the UE specific IDsto initialize the scrambling sequences is also the solution.

According to the present embodiment, for a transmission point device(for example, 700, 1000) or a UE (for example, 800), the signals may beone of RSs, control signals for control channels, and data signals fordata channels. That is, according to the present embodiment, signals,either control signals for control channels or data signals for datachannels, may be scrambled by a scrambling sequence initialized by arandom seed generated based on a UE specific ID, or according to thepresent embodiment, signals, either control signals for control channelsor data signals for data channels, may also be scrambled by a scramblingsequence initialized by a random seed which is selected from a firstrandom seed generated based on a transmission point specific ID and asecond random generated based on a UE specific ID.

In LTE (release-8, 9) and LTE-A (release-10), the downlink controlchannel (PDCCH) is based on CRS (Control Reference Signal) which is usedas the RS for demodulation, and CRS is transmission point specificwithout precoding. However, for release-11 or latter release, it islikely that the PDCCH is enhanced to E-PDCCH (Enhanced PDCCH) byutilizing DMRS as the reference signal to demodulate. In this case, theidea as described above can also be applied to DMRS based E-PDCCH: 1)DMRS random seed can be generated based on a UE specific ID; 2) The DMRSrandom seed can be switched between a UE specific random seed and atransmission point specific random seed (such as release-10 randomseed).

In addition to the reasons mentioned before, there is another advantageof generating a random seed for DMRS of E-PDCCH based on a UE specificID: when a UE detects E-PDCCH, the UE is unaware of the potential DMRSconfigurations because E-PDCCH is a control channel. Thus, if E-PDCCHuses the release-10 DMRS random seed, the UE needs at least to “guess”whether it uses SCID=0 or 1. However, if E-PDCCH uses a UE specific DMRSrandom seed, the UE knows the DMRS random seed on detecting the E-PDCCHsince the UE specific ID such as c-RNTI has already been assigned to theUE at this stage.

Fourth Embodiment

The first to third embodiments as described above all use a random seedgenerated based on a UE specific ID to initialize the scramblingsequence for scrambling signals. However, it is noted that the ID onwhich a random seed is generated is not limited to the UE specific ID.It is also possible to generate the random seed based on a group IDwhich can also be referred to as a common ID. The group ID means that agroup of UEs can share one ID, which is different from the case of usinga UE specific ID as a random seed. As an example, equation (5) is usedfor generating the random seed for initializing a scrambling sequencefor signals based on a group ID as follows.

c _(init)=(└n _(s)/2┘+1)·(2group_id+1)·2¹⁶   (5)

Wherein, c_(init) represents the random seed, n_(s) represents the slotnumber, and group_id represents the group ID.

Comparing the equation (5) with the equation (1), it is found that thedifference between two equations is that the cell_id in the equation (1)is replaced by the group_id in the equation (5) and the SCID is notinvolved in the equation (5). For the equation (1), a UE knows thecell_id through a transmission point specific way, i.e., a broadcastingchannel. Similarly, for the equation (5), the group_id can be assignedby a transmission point device and notified to the UE by a UE specificsignaling.

By using the group_id, the random seed requirements including the samerandom seed in JT operation and different random seeds in non-CoMPoperation, as shown in FIG. 4, can be satisfied through the transmissionpoints assigning the same or different group_id to the UE(s)respectively.

However, in the MU operation, it is likely that a release-11 UE and arelease-10 UE may coexist. In this case, if the release-11 UE uses therandom seed generated by the equation (5), then the release-10 UE cannottake blind detection for MU interference of release-11 UEs. To solvethis problem, the idea of the third embodiment as described above canalso be used in the present embodiment. That is, for the MU operation,release-10 random seeds as generated by the equation (1) based ontransmission point IDs are used to initialize the scrambling sequencesfor scrambling signals. In other cases such as JT operation and non-CoMPoperation, random seeds generated by the equation (5) are used.

According to the present embodiment, a transmission point device (forexample, 1000) may further include a notification unit which notifiesthe group ID to the UE by UE specific signaling. The second random seedis generated from the equation (5) including the group ID.

According to the present embodiment, in a UE (for example, 800), thetransceiver unit may further receive UE specific signaling whichindicates the group ID from a transmission point. The second random seedis generated from the equation (5) including the group ID.

Fifth Embodiment

FIG. 14 is a diagram showing a flow chart of a method of scramblingsignals according to the fifth embodiment of the present disclosure.

As shown in FIG. 14, the method 1400 according to the fifth embodimentof the present disclosure is used for scrambling signals assigned onpredetermined radio resources of at least one layer of resource blockswith the same time and frequency resources. In the step S1401, a randomseed is generated based on a UE specific ID. In the step S1402, ascrambling sequence is initialized by the random seed. In the stepS1403, the signals are scrambled with the initialized scramblingsequence.

According to the present embodiment, the above step S1401 can beexecuted by the random seed generation unit 701, the above step S1402can be executed by the initiation unit 702, and the above step S1403 canbe executed by the scrambling unit 703.

According to the present embodiment, the user equipment specific ID maybe a global user equipment specific identification number.

According to the present embodiment, the user equipment specific ID maybe International Mobile Subscriber Identification Number.

According to the present embodiment, the user equipment specific ID maybe a user equipment specific ID assigned to a user equipment when theuser equipment accesses to a LTE network.

According to the present embodiment, the user equipment specific ID maybe c-RNTI.

According to the present embodiment, although not shown in FIG. 14, themethod 1400 may further include a step of generating the random seedbased on the equation (2).

According to the present embodiment, although not shown in FIG. 14, themethod 1400 may further include a step of generating the random seedbased on the equation (3).

According to the present embodiment, the signals may be one of referencesignals, control signals for control channels, and data signals for datachannels.

According to the present embodiment, the signals may be DemodulationReference Signals.

According to the present embodiment, although not shown in FIG. 14, themethod 1400 may further include a step of transmitting the resourceblocks with the scrambled signals from a transmission point to a userequipment or from the user equipment to the transmission point. Thisstep may be executed by the transceiver unit 704 of the transmissionpoint device 700 and the transceiver unit 801 of the UE 800.

According to the present embodiment, by generating random seeds forinitializing the scrambling sequences for signals based on the UEspecific IDs, the conflict requirements on random seeds for the JTscenario and the non-CoMP scenario are solved.

Sixth Embodiment

FIG. 15 is a diagram showing a flow chart of a method of scramblingsignals according to the sixth embodiment of the present disclosure.

As shown in FIG. 15, the method 1500 according to the present embodimentis used for scrambling signals assigned on predetermined radio resourcesof at least one layer of resource blocks with the same time andfrequency resources. In the step S1501, a random seed is selected from afirst random seed generated based on a transmission point ID and asecond random seed. In the step S1502, a scrambling sequence isinitialized by the selected random seed. In the step S1503, the signalsare scrambled with the initialized scrambling sequence.

According to the present embodiment, the above step S1501 can beexecuted by the selection unit 1001, the above step S1502 can beexecuted by the initiation unit 1002, and the above step S1503 can beexecuted by the scrambling unit 1003.

According to the present embodiment, the second random seed may begenerated based on a group ID assigned by a transmission point.

According to the present embodiment, although not shown in FIG. 15, themethod 1500 may further include a step of notifying the group ID to auser equipment by user equipment specific signaling. This step may beexecuted by a notification unit (not shown in FIG. 10) of thetransmission point device 1000.

According to the present embodiment, the second random seed may begenerated from the equation (5).

According to the present embodiment, the second random seed may begenerated based on a user equipment specific ID.

According to the present embodiment, the method 1500 may further includea step of notifying a receiver side of the selection of the first randomseed and the second random seed by adding one bit signaling as a switchflag. This step may be executed by a notification unit (not shown inFIG. 10) of the transmission point device 1000. According to the presentembodiment, the method 1500 may further include a step of notifying areceiver side of the selection of the first random seed and the secondrandom seed by using signaling set with one codeword, wherein, sevenvalues in the one codeword respectively indicate the following sevencases: one layer of signals configured with a first port and the secondrandom seed; one layer of signals configured with the first port and thefirst random seed; one layer of signals configured with a second portand the second random seed; one layer of signals configured with thesecond port and the first random seed; two layers of signals configuredwith the first and the second ports and the second random seed; threelayers of signals configured with the first, the second and a thirdports and the second random seed; and four layers of signals configuredwith the first to the third ports and a fourth port and the secondrandom seed. This step may be executed by a notification unit (not shownin FIG. 10) of the transmission point device 1000.

According to the present embodiment, the method 1500 may further includea step of notifying a receiver side of the selection of the first randomseed and the second random seed by using signaling set with twocodewords, wherein, eight values in the two codewords respectivelyindicate the following eight cases: two layers of signals configuredwith the first and the second ports and the second random seed; twolayers of signals configured with the first and the second ports and thefirst random seed; three layers of signals configured with the first,the second and the third ports and the second random seed; and fourlayers of signals configured with the first to the fourth ports and thesecond random seed; five layers of signals configured with the first tothe fourth ports and a fifth port and the second random seed; six layersof signals configured with the first to the fifth ports and a sixth portand the second random seed; seven layers of signals configured with thefirst to the sixth ports and a seventh port and the second random seed;and eight layers of signals configured with the first to the seventhports and a eighth port and the second random seed. This step may beexecuted by a notification unit (not shown in FIG. 10) of thetransmission point device 1000.

According to the present embodiment, the first random seed is generatedfrom the equation (1).

According to the present embodiment, the method 1500 may further includea step of notifying a receiver side of the selection of the first randomseed and the second random seed by using signaling set with onecodeword, wherein, eight values in the one codeword respectivelyindicate the following eight cases: one layer of signals configured witha first port and the first random seed with SCID=0; one layer of signalsconfigured with the first port and the first random seed with SCID=1;one layer of signals configured with a second port and the first randomseed with SCID=0; one layer of signals configured with the second portand the first random seed with SCID=1; two layers of signals configuredwith the first and the second ports and the second random seed; threelayers of signals configured with the first, the second and a thirdports and the second random seed; four layers of signals configured withthe first to the third ports and a fourth port and the second randomseed; and one layer of signals configured with the first port or thesecond port and the second random seed. This step may be executed by anotification unit (not shown in FIG. 10) of the transmission pointdevice 1000.

According to the present embodiment, the second random seed is differentfrom the first random seed.

According to the present embodiment, the second random seed is generatedfrom the equation (3).

According to the present embodiment, the signals are one of referencesignals, control signals for control channels, and data signals for datachannels.

According to the present embodiment, the method 1500 may further includea step of transmitting the resource blocks with the scrambled signalsfrom a transmission point to a user equipment or from the user equipmentto the transmission point. This step may be executed by the transceiverunit 1004 of the transmission point device 1000 and the transceiver unit801 of the UE 800.

According to the present embodiment, by switching between transmissionpoint specific random seeds and UE specific random seeds or random seedsgenerated based on group IDs assigned by transmission points, the blinddetection can be enabled and the orthogonality between UEs can be keptin MU operation, while the conflict requirements for both JT andnon-CoMP operations can be solved in non-MU operation.

Seventh Embodiment

As described above in the fourth embodiment, by using a group ID togenerate a random seed, the random seed requirements in JT operation andin non-CoMP operation, as shown in FIG. 4, can also be satisfied.However, with being different from using a UE specific ID to generatethe DMRS seed (in that case, the UE specific ID is already known to UE),a group ID needs to be notified to a UE side in a case of using thegroup ID to generate a DMRS seed. The present embodiment will focus onhow to notify a group ID to a UE.

Two issues need to be decided when a group ID is used to generate a DMRSrandom seed:

1) How many group IDs are necessary to facilitate different scenarios(CoMP, non-CoMP, MU scenarios) as described in the BACKGROUND part, and

2) How to notify UE which group ID is to be used, i.e. by higher layersignaling or by physical layer signaling.

For the question 1), cases for different scenarios are different.Specifically, if group IDs are used in CoMP or non-CoMP scenarios, thena large range of group IDs may be helpful to avoid ICI due to DMRS. Onthe other hand, if group IDs are used in a MU operation, then a smallrange of group IDs may benefit MU blind detection.

For the question 2), the solution also depends on the scenario wheregroup IDs are used. Specifically, if a UE is on the boundary of atransmission point (cell) and fast switches between CoMP and non-CoMPstates, fast configuration of the group IDs is necessary (higher layersignaling cannot track such switch), then physical layer signaling isnecessary. Similar things also hold when a UE is in the center of atransmission point (cell) and fast switches between MU & non-MU states.However, if a UE moves from the center to the edge of a transmissionpoint (cell) and needs to reconfigure the DMRS random seed, then higherlayer signaling is enough.

Therefore it is seen that depending on specific cases where group IDsare used, a large or small range of group IDs and higher layer signalingor physical layer signaling can both satisfy some kinds of scenarios. Ifa large range of group IDs and physical layer signaling are always used,it means a great waste. So how to choose a proper range of group IDs andthe way to configure them to a UE is a critical issue.

In this embodiment, it is proposed to combine higher layer signaling andphysical layer signaling to solve this problem. A proposed method forconfiguring (sending) a group ID to a UE consists of 2 steps:

1) A group ID table is configured (sent) to a UE through higher layersignaling. Wherein, this table contains available group IDs that the UEcan use. The whole range of group IDs may be large, but a network sidecan configure and send a subset of the whole group ID space to a UE.

2) After the group ID table is configured (sent) to the UE, physicallayer signaling is used to notify the UE which group ID in the group IDtable is to be used.

The basic idea of this embodiment is illustrated in FIG. 16. FIG. 16 isa schematic diagram showing the configuration of group IDs according tothe present embodiment. In FIG. 16, three macro cells (macrotransmission point) 1-3 are shown. In the macro cell 1, MU operation isperformed and there are eNB1 and four UEs 1-4. In the macro cell 2, JT(CoMP) operation is performed and there are eNB2, two LPNs (Lower PowerNodes) 1-2 and UE 5, wherein the eNB2, LPN 1, and LPN 2 all havedifferent transmission point (cell) IDs respectively. In the macro cell3, non-CoMP operation is performed and there are eNB3, four LPNs 1-4 andthree UEs 6-8, wherein the eNB3, LPN 1, LPN 2, LPN 3, LPN 4 all have thesame transmission point (cell) ID. Here, an eNB or a LPN may also bereferred to as a transmission point (device).

For these three macro cells performing three different kinds ofoperations, the network side configures (sends) different group IDtables to UEs in different macro cells through higher layer signalingrespectively. Each group ID table contains two parts, i.e., “index” and“information” which respectively indicate indexes and the correspondinggroup IDs which are available to UEs, as shown in FIG. 16.

Specifically, as shown in FIG. 16, the UEs 1-4 in the macro cell 1 areconfigured with the group ID table on the left side of the figure inwhich two indexes 0, 1 and their corresponding group IDs, i.e. group ID1 and group ID 2 are contained. As described above with reference toFIG. 6, two random seeds for UEs 1-4 in MU operation can satisfy therequirement of MU blind detection, thus two available group IDs areenough for the macro cell 1.

For the macro cell 2, since the eNB2, LPN 1, LPN 2 have differenttransmission point (cell) IDs respectively, different DMRS random seedsgenerated based on their different transmission point IDs cannot meetthe random seed requirement for JT operation as described in theBACKGROUND part. Accordingly, group ID is used here to generate DMRSrandom seed so as to meet the requirement. Specifically, UE 5 isconfigured with the group ID table in the middle of the figure in whichthree indexes 0, 1, 2 and their corresponding group IDs, i.e. group ID3, group ID 4 and group ID 5 are contained. It is noted here that threeavailable group IDs are provided since three transmission points, thatis, eNB2 and LPNs 1-2, exist in the macro cell 2.

For the macro cell 3, since the eNB3, LPN 1, LPN 2, LPN 3, LPN 4 allhave the same transmission point (cell) ID, the same DMRS random seedgenerated based on their same transmission point ID cannot meet therandom seed requirement for non-CoMP operation as described in theBACKGROUND part. Accordingly, group ID is used here to generate DMRSrandom seed so as to meet the requirement. Specifically, UEs 6-8 areconfigured with the group ID table on the right side of the figure inwhich five indexes 0-4 and their corresponding group IDs 6-10 arecontained. Here, five available group IDs are provided since fivetransmission points, that is, eNB3 and LPNs 1-4, exist in the macro cell3.

As described above, a group ID table configured to a UE may contain themaximum number of group IDs to be possibly used by the UE and it is asubset of the whole group ID space. As shown in FIG. 16, the whole groupID space may contain a large number of group IDs, for example, fromgroup ID 1 to group ID N. However, the number of group IDs in the groupID table configured to a UE is limited. Thus, only a small range ofindexes is enough for each UE.

When a UE is configured with a group ID table through higher layersignaling from the network side, an transmission point device (eNB) usesphysical layer signaling to notify the UE which group ID is to be usedin the group ID table or to notify the UE the used “index” in the groupID table. Specifically, for the macro cell 1, for example, bynotification of eNB1, DMRSs for UE 1 and UE 3 are scrambled with ascrambling sequence which is initiated by a random seed generated basedon the index 0, i.e. group ID 1, and DMRSs for UE 2 and UE 4 arescrambled with a scrambling sequence which is initiated by a random seedgenerated based on the index 1, i.e. group ID 2.

For the macro cell 2, although the group ID table configured to UE 5contains three available group IDs 3-5, in fact, the three availablegroup IDs may not be used entirely. For example, for JT operation ofdifferent transmission points, the same random seed is generated basedon one of available group IDs in the configured group ID table asdescribed above with reference to FIG. 4. Therefore, for example, asshown in FIG. 16, through physical layer signaling from eNB2 and LPN2,UE 5 is notified that the same random seed for both eNB 2 and LPN 2 isgenerated based on index 0, i.e. group ID 3.

The macro cell 3 is discussed now. As described with reference to FIG.4, for non-CoMP operation of adjacent transmission points, differentDMRS random seeds generated based on different group IDs is required foravoiding ICI due to DMRS. Thus, as shown in FIG. 16, for the operationof two adjacent interfering transmission points eNB3 and LPN 2 whichrespectively transmit signals to UE 7 and UE 6, UE 7 is notified throughphysical layer signaling from eNB3 that the random seed for eNB3 isgenerated based on index 2, i.e. group ID 8 while UE 6 is notifiedthrough physical layer signaling from LPN 2 that the random seed for LPN2 is generated based on index 0, i.e. group ID 6. Similarly, for theoperation of two adjacent interfering transmission points eNB3 and LPN 4which respectively transmit signals to UE 7 and UE 8, UE 8 is furthernotified through physical layer signaling from LPN 4 that the randomseed for LPN 4 is generated based on index 4, i.e. group ID 10.

Note that, there is a possibility that different kinds of operationsexist at the same time in a macro cell. For example, as shown in themacro cell 3 of FIG. 16, two transmission points LPN 2 and LPN 1transmit signals to the same UE, i.e. UE 6, which is a case of JToperation. Thus, the DMRS for LPN 1 should be the same as that for LPN 2and accordingly UE 6 is notified through physical layer signaling fromLPN 1 that the random seed for LPN 1 is generated based on index 0, i.e.group ID 6 which is the same as that for LPN 2.

In FIG. 16, each macro cell is assigned different subsets of group IDs,which could be a simple strategy of assigning group IDs to transmissionpoints (cells). However, the present disclosure is not limited thereto,and it is also possible that there are overlaps among group IDs assignedto different transmission points (cells).

According to the present embodiment, a transmission point device (forexample, 700) may further comprises a notification unit (not shown)which notifies the UE which group ID in a group ID table configured(sent) to the UE through higher layer signaling is to be used throughphysical layer signaling, in which the group ID table is a subset of thewhole group ID space and it contains available group IDs for the UE.Accordingly, the random seed generation unit (for example, 701) of thetransmission point device generates a random seed based on the notifiedgroup ID.

According to the present embodiment, a UE (for example, 800) may furtherreceives by its transceiver unit (for example, 801) physical layersignaling from a transmission point device, wherein the physical layersignaling notifies the UE which group ID in a group ID table configured(sent) to the UE through higher layer signaling is to be used, whereinthe group ID table is a subset of the whole group ID space and containsavailable group IDs for the UE.

With the group ID table described in this embodiment, the system has theflexibility to facilitate different cases: in some cases, for examplewhen a UE needs fast switching among different DMRS random seeds,physical layer signaling can be used; in some other cases, for examplewhen a UE moves from the center to the edge of a transmission point(cell), the system can reconfigure the group ID table for the UE throughthe higher layer signaling. Due to the feasibility of reconfiguration ofa group ID table, each group ID table can contain a limited number ofgroup IDs, which means that the signaling overhead of using physicallayer signaling to notify the UE which group ID in the group ID table isto be used is not very high.

Eighth Embodiment

Although combining higher layer signaling and physical layer signalingto configure a group ID to a UE provides the flexibility to meetdifferent requirements on DMRS random seeds, one remaining problem ishow to decide the blind detection space for a UE. One straightforwardway is that the UE regards the group ID table configured from high layersignaling as the blind detection space (UE assumes that all group id inthe table may generate interference to it). However, the number of groupIDs contained in the group ID table may change, for example, as shown inFIG. 16, the group ID tables configured to the macro cells 1-3respectively contain two, three and five available group IDs.Furthermore, on design of a blind detector, a UE needs to facilitate themaximum blind detection space, that is, maximum number of potentialinterfering random seeds. Therefore, the method of regarding the entiregroup ID table as the blind detection space will degrade the blinddetection performance or reliability. Recall that in rel-10, the blinddetection space is restricted into only 2 random seeds as described inthe BACKGROUND part with reference to FIG. 6.

Thus, the solution of the present embodiment is that the physical layersignaling described in the seventh embodiment contains two parts:

Part I: notify the UE which group ID in the group ID table is to be usedfor the UE; and

Part II: notify the UE which group IDs in the group ID table are to beused for another UE which interferes with the UE.

In such case, the blind detection space for the UE is composed of thegroup ID notified by Part I and the group IDs notified by Part II. Thus,the blind detection on the UE side is then performed within the blinddetection space notified from Part I and Part II of the physical layersignaling.

By notifying a UE of the blind detection space through physical layersignaling, the blind detection space for the UE may be limited insteadof being the entire group ID table.

Ninth Embodiment

In the eighth embodiment, both the group ID for the UE notified fromPart I and the group IDs for the another UE notified from Part II areselected from the group ID table configured (sent) to the UE throughhigher layer signaling. In other words, the candidate group IDs for PartI and Part II are the same, both from the configured group ID table.

However, in fact, for Part II, the another UE could be a UE in the sametransmission point (cell) as that of the UE (MU case) or in a differenttransmission point (cell) from that of the UE, that is, candidate groupIDs for Part I and Part II could be same or different according todifferent cases. For example, for a MU case where UEs are near center ofa transmission point (cell), UEs may switch quickly between MU and SUstates, thus candidate group IDs for Part I and Part II are the same,both from the group ID table configured (sent) to the UE through higherlayer signaling. On the other hand, when a UE moves to the edge of atransmission point (cell), the another UE is most likely in a neighbortransmission point (cell) and accordingly the candidate group IDs forPart II is most likely from the group ID table configured to theneighbor transmission point (cell). In such a case, candidate group IDsfor Part I and Part II are different.

Based on the above analysis, it is proposed to configure (sent) astructured group ID table to a UE through higher layer signaling, suchas RRC (Radio Resource Control), in the present embodiment.Specifically, a structured group ID table configured to a UE throughhigher layer signaling may consist of two sets, for example, Set 1 andSet 2, wherein: the group ID to be used for DMRS random seed for the UEis selected from Set 1, or Part I of the physical layer signaling asdescribed above is within Set 1; and the group ID to be used for DMRSrandom seed for another UE interfering with the UE is selected from Set1 or Set 2, or Part II of the physical layer signaling is within Set 1or Set 2.

FIG. 17 shows an example of a structured group ID table configured to aUE through higher layer signaling according to the present embodiment.One detailed example is shown in FIG. 17. In the structured group IDtable, for example, Set 1 and Set 2 each contain two group IDs.Specifically, Set 1 contains two indexes 0, 1 and the correspondinggroup IDs, i.e. id 0 and id 1, while Set 2 contains two indexes 2, 3 andthe corresponding group IDs, i.e. id 2 and id 3. One case is that Set 1is used in a local transmission point (cell) and Set 2 is used for aninterfering transmission point (cell). That is, id 0 and id 1 in Set 1are two available group IDs for UEs in the local transmission point, andid 2 and id 3 in Set 2 are two available group IDs for UEs in theinterfering transmission point.

Accordingly, for a MU case (for example, near the center of the localtransmission point), group IDs notified by Part I and Part II of thephysical layer signaling are both selected from Set 1 of the structuredgroup ID table since the UE itself and the interfering UE (another UEinterfering with the UE) are both in the local transmission point. Onthe other hand, when a UE moves to the edge of the local transmissionpoint, the group ID notified by Part I is still selected from Set 1while the group ID by Part II is selected from Set 2 since theinterfering UE is most likely in the interfering transmission point suchas an adjacent transmission point to the local transmission point wherethe UE itself is located.

As described above, the group ID notified by Part I of physical layersignaling is always selected from Set 1 of the structured group ID tableconfigured to a UE while the group ID by Part II is selected either inSet 1 or in Set 2. Thereby, in such a case, only 1 bit is required forPart I and Part II respectively in physical layer signaling. The otheroverhead is 1 bit signaling to indicate the switch between Set 1 and Set2 for selection of the group ID notified by Part II, which is not veryfrequently sent because it generally occurs with UE's mobility.

Without this structured group ID table, in the case that there are fourcandidate group IDs in total, 2 bits are required for Part I and Part IIrespectively. Therefore, 50% physical layer signaling overhead reductionis achieved due to the structured group ID table configured (sent) to aUE through higher layer signaling.

Although each set of the structured group ID table configured to the UEthrough higher layer signaling contains two available group IDs in thisembodiment, the present disclosure is not limited thereto and the methodof the disclosure may be extended to cases of multiple layers of signalsmultiplexed, that is, each set of the structured group ID tableconfigured to the UE through higher layer signaling may contain multipleavailable group IDs for multiple layers of signals.

In the next embodiment, we will use a detailed example to further showhow to design the corresponding physical layer signaling with thestructured group ID table.

Tenth Embodiment

In the third embodiment as described above, it has showed how to re-usea table as defined in TS 36.212 shown in FIG. 11 to notify a UE of DMRSports and DMRS random seeds. In the present embodiment, a similar methodcan be re-designed to facilitate the structured group ID tableconfigured (sent) to a UE through high layer signaling as describedabove. Specifically, physical layer signaling may consist of threeparts:

Part I: notify the UE which group ID selected from Set 1 is to be usedfor DMRS for this UE;

Part II: notify the UE which group ID selected from Set 1 or Set 2 is tobe used for another UE interfering with this UE; and

Part III: notify the UE of the switch between Set 1 and Set 2 as theinterfering random seed space (interfering group ID space) from whichthe group ID notified by Part II is selected.

FIG. 18 shows a table used for Part I of physical layer signalingaccording to the present embodiment. For Part I, the table shown in FIG.11 may be re-designed as in the table shown in FIG. 18. For the purposeof simplicity, only a case of one codeword with one layer multiplexed isillustrated in FIG. 18, but it is not limiting of the presentdisclosure. As shown in FIG. 18, with respect to same values 0-4, twocolumns “Message, Rel-10” and “Message, Rel-11” respectively indicatethe corresponding combinations of DMRS ports and random seeds inrelease-10 and release-11. Specifically, in release-11, DMRS portscorresponding to the values are same as those in release-10, and thegroup ID (i.e. index) used for the DMRS random seed may be indicated bySCID in release 10. Thereby, no new bit is required for notifying a UEof the DMRS random seed. Here, “index” in the table of FIG. 18represents the “index” in the structured group ID table of FIG. 17.

For Part II, one additional new bit is required to notify the UE of theexact index corresponding to the group ID to be used for the interferingUE (the another UE interfering with the UE) in the structured group IDtable as shown in FIG. 17.

FIG. 19 shows a table used for Part III of physical layer signalingaccording to the present embodiment. For Part III, the table in FIG. 11can be re-designed as in the table shown in FIG. 19. Specifically, thepreviously reserved value “7” in release-10 is now re-used as a switchsignal indicating the switch of the interfering random seed space(interfering group ID space), for example between Set 1 and Set 1 in thestructured group ID table as shown in FIG. 17.

It is easily found that Part I and Part III are both notified to a UEthrough the current L1 signaling (for example, the current DCI format2C), thus only one of Part I and Part III can be notified to the UEthrough the current L1 signaling every time when sending physical layersignaling to the UE. Subsequently, the next question is which DMRSrandom seed and which DMRS port are to be used for the UE when atransmission point device such as an eNB send the reserved value (“7”)to the UE. To solve it, it is possible to set the following rules forthis case:

1) the additional new bit in this case is used to indicate the group IDto be used for the DMRS random seed for the UE in Set 1, that is, Part Iinstead of Part II, to the UE;

2) the UE is fixed to use port 7 (OCC [1,1]) or port 8 (OCC [1,−1]); and

3) the blind detection space for the UE in this case is within Set 1.

FIG. 20A and 20B are schematic diagrams showing a complete example wherea transmission point use the higher layer signaling and physical layersignaling as defined in the ninth and the tenth embodiments to configurea UE when the UE moves from the center to the edge of the transmissionpoint.

As shown in FIG. 20A, there are two cells (transmission points) 1-2(eNB1 and eNB2). In the transmission point 1, it is assumed that UE 1and UE2 are in MU operation at time T1, thus UE2 is the interfering UEto UE 1 at this time. Then, UE 1 is moving from the center to the edgeof the transmission point 1 at time T2. Thereafter, at time T3, UE 1arrives at the edge of the transmission point 1, and UE 3 in thetransmission point 2 become the UE interfering with UE 1 at this time.

In this example, UE 1 is configured with the structured group ID tableas shown on the left of the figure through higher layer signaling suchas RRC. The structured group ID table for UE 1 contains two sets“Serving cell” and “Interfering cell”, which are named for betterexpressing its content and substantially equivalent to Set 1 and Set 2as defined above. Specifically, the set of “Serving cell” contains twoavailable group IDs for UE 1 and it is a subset of the whole group IDspace and assigned to UEs in the transmission point 1 which functions asthe serving cell (transmission point) for UE 1. The set of “Interferingcell” contains two available group IDs for UEs in the interfering cell(transmission point) to UE 1, for example the transmission point 2 inthis example, and is also a subset of the whole group ID space. It iseasily seen in this example that id 0 and id 1 in “Serving cell” areavailable group IDs for UE 1 and UE 2 and id 2 and id 3 are availablegroup IDs for UE 3.

Similarly, UE 3 is also configured with the structured group ID table asshown on the right of the figure through higher layer signaling such asRRC. In contrast to UE 1, for UE 3, its serving cell (transmissionpoint) is the transmission point 2 and its interfering cell(transmission point) is the transmission point 1, thus “Serving cell”contains id 2 and id 3 as available group IDs for UE 3 while“Interfering cell” contains id 0 and id 1 as available group IDs for UEsin the interfering cell to UE 3, for example the transmission point 1 inthis example.

As described above, FIG. 20A shows the structured group ID tablesconfigured (sent) to UEs through higher layer signaling in this example.In the following, with reference to FIG. 20B, notification to UE 1through physical layer signaling (L1 signaling) during the time when UE1 moves from the center to the edge of the transmission point 1 will bediscussed in detail.

On the top of FIG. 20B, the L1 signaling sent to UE 1 at time Ti isshown. Specifically, UE 1 is notified to use port 7 and id 0 with value“0” by re-designing the table as shown in FIG. 11 as described above. Inaddition, one additional new bit is used to notify UE 1 of the group IDto be used for the interfering UE, for example, “1” indicates id 1. Thatis because at time T1 UE 1 and UE 2 are in MU operation, that is, UE 2is considered as the interfering UE to UE 1. In this case, theinterfering random seed space is just the range of “Serving cell” in thestructured group ID table configured to UE 1, therefore, the blinddetection space for UE 1 is defined as within “Serving cell”.

In the middle of FIG. 20B, the L1 signaling sent to UE 1 at time T2 isshown. Specifically, UE 1 is notified of the switch of the interferingrandom seed space with value “7” which is reserved in the table as shownin FIG. 11 by re-designing, which means that the interfering random seedspace will be changed from “Serving cell” to “Interfering cell”. Then,different from T1, at T2 the additional new bit is now used to notify UE1 of the group ID to be used for its own DMRS random seed, for example,“0” indicates id 0. According to the rules as described above, in suchcase, UE 1 is fixed to port 7 or port 8, thus no additional bit isrequired to notify UE 1 which DMRS port is to be used. Furthermore,since UE 1 is in motion at T2, its interfering UE is not required to benotified to UE 1 and accordingly no other new bit is necessary. In suchcase, according to the rules as described above, the blind detectionspace remains unchanged, that is, within “Serving cell” in thestructured group ID table for UE 1.

On the bottom of FIG. 20B, the L1 signaling sent to UE 1 at time T3 isshown. At this time UE 1 has arrived at the edge of the transmissionpoint 1, thus the L1 signaling at this time is similar with that of T1.Specifically, UE 1 is still notified to use port 7 and id 0 with value“0” by re-designing the table as shown in FIG. 11 as described above. Inaddition, one additional new bit in L1 signaling is also used to notifyUE 1 of the group ID to be used for the interfering UE. Since now theinterfering UE is UE 3 in the transmission point 2 instead of UE 1 inthe transmission point 1 and UE 1 is already notified of the switch ofthe interfering random seed space at T2, the interfering random seedspace is now “Interfering cell” in the structured group ID table for UE1, and the group ID to be used for the interfering UE at this time isselected from “Interfering cell”, for example, “1” here indicates id 3.In this case, the blind detection space for UE 1 is defined as withinthe range of the DMRS random seed for UE 1 and the interfering randomseed (the random seed for the interfering UE), that is, id 0 and id 3.

By fully utilizing the redundancy on the current L1 signaling toindicate the blind detection space to a UE for a MU case or a UE sideICIC case, the blind detection space of the UE is limited and thesignaling overhead is reduced.

Eleventh Embodiment

One problem of the tenth embodiment is that it is possible that physicallayer signaling is lost due to PDCCH detection failure. FIG. 21 is aschematic diagram showing a case that physical layer signaling is lostdue to PDCCH failure according to the present embodiment. As shown inFIG. 21, if eNB sends UE a reserved value (Part III) to notify UE of theswitch between Set 1 and Set 2 as described above, but UE does notreceive it, then there will be asynchronization between eNB and UE. Thatis, eNB may have switched the interfering random seed space (interferinggroup ID space) for example from Set 1 to Set 2 while UE still maintainthe interfering random seed space unchanged. The solution is to combinean Ack/Nck (Acknowledge/Non-acknowledge) process to overcome such PDCCHdetection failure.

Now, as an example, a DL (Downlink) Ack/Nck process is brieflyintroduced as follows. In LTE or LTE-A, in order to prevent physicallayer message loss, there is an Ack/Nck mechanism between UE and eNB.Specifically, for DL, on subframe n (SF n), if UE receives a message andsuccessfully decode it, UE will send Ack signal to eNB on subframe n+4(SF n+4); if UE receives a message and decode it in error, UE will sendNck signal to eNB on SF n+4. Based on the Ack or Nck signal from UE onSF n+4, eNB will know if the message sent on SF n is successfullyreceived and decoded by UE. If eNB receives nothing on SF n+4, eNB willassume that the message sent on SF n is lost during transmission.

Combined with such an Ack/Nck process, the asynchronization between eNBand UE can be avoided. FIG. 22 is a schematic diagram showing a casethat the asynchronization between eNB and UE is avoid by combining withthe Ack/Nck mechanism according to the present embodiment. As shown inFIG. 22, if UE receives a reserved value “7” or a switch commend on SFn, UE and eNB will not change or switch the interfering random seedspace immediately. Instead, UE and eNB will use the un-switchedinterfering random seed space until SF n+4 and UE sends Ack/Nck signalto eNB on SF n+4. On SF n+5, if eNB receives the Ack/Nck signal sentfrom UE, both the eNB and UE switch the interfering random seed spacesynchronously; if eNB receives nothing from UE, neither eNB nor UEswitches the interfering random seed space. This procedure intends forthe exception case that although eNB sends a switch command on SF n toUE, UE actually receives nothing (maybe due to the severe channelcondition).

With respect to the switch of the interfering random seed space (or theblind detection space), by combining with an Ack/Nck mechanism, theasynchronization between eNB and UE can be avoided.

Although physical layer signaling is used to notify a UE of a group IDto be used for the UE and a group ID to be used for another UEinterfering with the UE in the seventh to tenth embodiments, the presentinvention is not limited thereto. It should be noted that it is alsopossible that using UE specific higher layer signaling such as RRCsignaling to notify a UE about the indexes (group IDs) of DMRS randomseed (for the UE) and interfering DMRS random seed (for the interferingUE) based on a group ID table or a structured group ID table configured(sent) to the UE from higher layer signaling previously. In this case,there is no worry about the loss of signaling in transmission since RRChas its own signaling protection mechanism.

According to the present embodiment, the notification unit (not shown)of a transmission point device (for example, 700) may notify the UEwhich group ID in a group ID table configured (sent) to the UE throughhigher layer signaling is to be used through physical layer signaling orUE specific higher layer signaling, in which the group ID table is asubset of the whole group ID space and it contains available group IDsfor the UE.

According to the present embodiment, a UE (for example, 800) may furtherreceives by its transceiver unit (for example, 801) physical layersignaling or UE specific higher layer signaling from a transmissionpoint device, wherein the physical layer signaling or the UE specifichigher layer signaling notifies the UE which group ID in a group IDtable configured (sent) to the UE through higher layer signaling is tobe used, wherein the group ID table is a subset of the whole group IDspace and contains available group IDs for the UE.

Twelfth Embodiment

In the present disclosure, three kinds of IDs, that is, cell ID, UEspecific ID and group ID, as described above can all be used for DMRSand blind detection. Although the forgoing seventh to eleventhembodiments all focus on configuration of a group ID table to a UE, thepresent disclosure is not limited to it. Instead, the group ID table asdescribed in the seventh embodiment (as shown in FIG. 16) or in theninth embodiment (as shown in FIG. 17), may be extended to a moregeneral case that it can be an “x” ID table. Such “x” ID could be onekind of ID or could be two or more kinds of IDs. When “x” ID is a groupID specifically, the seventh to eleventh embodiments are the exactexamples.

FIG. 23 shows an example of a structured “x” ID table configured to a UEthrough higher layer signaling according to the present embodiment. Inthe example of FIG. 23, “x” ID are two kinds of IDs, i.e. cell ID and UEspecific ID. Specifically, the structure of the “x” ID table in FIG. 23is similar with that of the group ID table in FIG. 17. The differencebetween them is that in FIG. 23 Set 1 contains serving cell ID 1 and UEspecific ID 1 as available IDs for the UE and Set 2 contains servingcell ID 2 and UE specific ID 2 as available IDs for an interfering UE tothe UE. That is to say, both cell ID and UE specific ID are availablefor the UE and the interfering UE in this case.

Recall that in the third embodiment on MU operation, a UE is switchedback to a cell ID case to enable the blind detection. However, with thestructured “x” ID table of FIG. 23, the UE specific ID can also beavailable to the UE side for the blind detection since the blinddetection space for the UE is within the structured “x” ID table and canbe further limited to a small range of IDs by combining physical layersignaling design.

Here, since the “x” ID table is structured with Set 1 and Set 2similarly as the structured group ID table in the ninth embodiment,corresponding physical layer signaling design in the tenth and eleventhembodiments can be re-used in this case, the detailed description ofwhich is omitted here for avoiding redundancy.

It is noted that “x” ID is not restricted to three kinds of ID asdescribed in the present disclosure. It is easy for those skilled in theart to extend it to any other kind of IDs.

Thirteenth Embodiment

FIG. 24 is a diagram showing a flow chart of a method of scramblingsignals according to the present embodiment.

As shown in FIG. 24, the method 2400 according to the thirteenthembodiment of the present disclosure is used for scrambling signalsassigned on predetermined radio resources of at least one layer ofresource blocks with the same time and frequency resources. In the stepS2401, an ID table is sent to a UE through higher layer signaling, theID table being a subset of the whole ID space and containing availableIDs for the UE. In the step S2402, the UE is notified of an ID in the IDtable to be used through physical layer signaling or UE specific higherlayer signaling. In the step S2403, a random seed is generated based onthe notified ID. In the step S2404, a scrambling sequence is initializedby the random seed. In the step S2404, the signals are scrambled withthe initialized scrambling sequence.

According to the present embodiment, the above step S2403 can beexecuted by the random seed generation unit 701, the above step S2404can be executed by the initiation unit 702, and the above step S2405 canbe executed by the scrambling unit 703. Further, the above step S2402can be executed by a notification unit (not shown) of the transmissionpoint device 700.

According to the present embodiment, the physical layer signaling maycomprise: a first part which notifies the UE which ID in the ID table isto be used for the UE; and a second part which notifies the UE which IDsin the ID table are to be used for another UE interfering with the UE.

According to the present embodiment, the ID table may be structured tocontain a first set and a second set, wherein the ID for use of the UEis selected from the first set, and the ID for use of another UEinterfering with the UE is selected from either the first set or thesecond set.

According to the present embodiment, the first part may be notified tothe UE by using signaling set with one codeword, wherein four values inthe one codeword respectively indicate the following four configurationcases of one layer of signals: a first port and a first ID; the firstport and a second ID; a second port and the first ID; and the secondport and the second ID. And the second part may be notified to the UE bya new bit.

According to the present embodiment, the physical layer signaling maycomprise: a first part which notifies the UE which ID in the first setof the ID table is to be used for the UE; and a third part whichnotifies the UE the switch between the first set and the second set asthe interfering ID space from which the ID to be used for the another UEis selected.

According to the present embodiment, the first part may be notified tothe UE by a new bit, and the third part may be notified to the UE byusing signaling set with one codeword in which a reversed valueindicates the switch between the first set and the second set. Wherein,the UE may be fixed to use a first port or a second port, and the blinddetection space for the UE may be unchanged.

According to the present embodiment, when the UE receives the third partsent from a transmission point device on subframe n, the UE may sendAcknowledge or Non-acknowledge signal to the transmission point deviceon subframe n+4. If the transmission point device receives theAcknowledge or Non-acknowledge signal sent from the UE, both thetransmission point device and the UE performs the switch on subframen+5; otherwise if the transmission point device receives neitherAcknowledge nor Non-acknowledge signal from the UE, neither thetransmission point device nor the UE performs the switch.

According to the present embodiment, the IDs in the ID table are one ormore of group ID, cell ID and UE specific ID.

According to the present embodiment, a random seed based on the group IDmay be generated from the equation (5).

According to the present embodiment, the signals may be one of referencesignals, control signals for control channels, and data signals for datachannels.

According to the present embodiment, by combining physical layersignaling and higher layer signaling to notify the used group ID and theblind detection space to a UE, the blind detection for the UE is enabledand the signaling overhead is reduced.

The foregoing detailed description has set forth various embodiments ofthe devices and/or processes via the use of block diagrams, flowcharts,and/or examples. Insofar as such block diagrams, flowcharts, and/orexamples contain one or more functions and/or operations, it will beunderstood by those skilled in the art that each function and/oroperation within such block diagrams, flowcharts, or examples can beimplemented, individually and/or collectively, by a wide range ofhardware, software, firmware, or virtually any combination thereof. Inone embodiment, several portions of the subject matter described hereinmay be implemented via Application Specific Integrated Circuits (ASICs),Field Programmable Gate Arrays (FPGAs), digital signal processors(DSPs), or other integrated formats. However, those skilled in the artwill recognize that some aspects of the embodiments disclosed herein, inwhole or in part, can be equivalently implemented in integratedcircuits, as one or more computer programs running on one or morecomputers (e.g., as one or more programs running on one or more computersystems), as one or more programs running on one or more processors(e.g., as one or more programs running on one or more microprocessors),as firmware, or as virtually any combination thereof, and that designingthe circuitry and/or writing the code for the software and or firmwarewould be well within the skill of one of those skilled in the art inlight of this disclosure. In addition, those skilled in the art willappreciate that the mechanisms of the subject matter described hereinare capable of being distributed as a program product in a variety offorms, and that an illustrative embodiment of the subject matterdescribed herein applies regardless of the particular type of signalbearing medium used to actually carry out the distribution. Examples ofa signal bearing medium include, but are not limited to, the following:a recordable type medium such as a floppy disk, a hard disk drive, aCompact Disc (CD), a Digital Video Disk (DVD), a digital tape, acomputer memory, etc.; and a transmission type medium such as a digitaland/or an analog communication medium (e.g., a fiber optic cable, awaveguide, a wired communications link, a wireless communication link,etc.).

With respect to the use of substantially any plural and/or singularterms herein, those having skills in the art can translate from theplural to the singular and/or from the singular to the plural as isappropriate to the context and/or application. The varioussingular/plural permutations may be expressly set forth herein for sakeof clarity.

While various aspects and embodiments have been disclosed herein, otheraspects and embodiments will be apparent to those skilled in the art.The various aspects and embodiments disclosed herein are for purposes ofillustration and are not intended to be limiting, with the true scopeand spirit being indicated by the following claims.

1. A communication apparatus comprising: circuitry, which, in operation,generates a reference signal, the reference signal being based on asequence that is initialized with a random seed, the random seed beingone of a first random seed generated based on a cell ID and a secondrandom seed generated based on a second ID that is dedicated to a userequipment (UE), wherein the first random seed is C_(init) generated byc _(init)=(└n _(s)/2┘+1)·(2cell_id+1)·2¹⁶+SCID wherein, n_(s) is a slotnumber, cell_id is the cell ID, and SCID is 0 or 1, and whether therandom seed is the first random seed or the second random seed isdetermined based on the SCID; and a transmitter, which, in operation,transmits the reference signal to the UE.
 2. The communication apparatusaccording to claim 1, wherein a plurality of second IDs are grouped intwo sets, and said transmitter, in operation, transmits information thatindicates one set out of the two sets.
 3. The communication apparatusaccording to claim 1, wherein the second ID is dedicatedly notified tothe UE.
 4. The communication apparatus according to claim 1, wherein thesecond ID is a group ID shareable by a plurality of UEs.
 5. Thecommunication apparatus according to claim 1, wherein the transmitter,in operation, transmits the reference signal that is scrambled with thesequence.
 6. The communication apparatus according to claim 1, whereinthe reference signal is a demodulation reference signal (DMRS).
 7. Acommunication method comprising: generating a reference signal, thereference signal being based on a sequence that is initialized with arandom seed, the random seed being one of a first random seed generatedbased on a cell ID and a second random seed generated based on a secondID that is dedicated to a user equipment (UE), wherein the first randomseed is C_(init) generated byc _(init)=(└n _(s)/2┘+1)·(2cell_id+1)·2¹⁶+SCID wherein, n_(s) is a slotnumber, cell_id is the cell ID, and SCID is 0 or 1, and whether therandom seed is the first random seed or the second random seed isdetermined based on the SCID; and transmitting the reference signal tothe UE.
 8. The communication method according to claim 7, wherein aplurality of second IDs are grouped in two sets, and the communicationmethod comprises transmitting information that indicates one set out ofthe two sets.
 9. The communication method according to claim 7, whereinthe second ID is dedicatedly notified to the UE.
 10. The communicationmethod according to claim 7, wherein the second ID is a group IDshareable by a plurality of UE.
 11. The communication method accordingto claim 7, wherein the transmitting includes transmitting the referencesignal that is scrambled with the sequence.
 12. The communication methodaccording to claim 7, wherein the reference signal is a demodulationreference signal (DMRS).